prereq-build.mk (git-core) check broken

Please, add this patch to solve problem with git detection: http://nbd.name/prereq-test3.patch

upstream ticket: https://dev.openwrt.org/ticket/21968

$ make V=s
...
Build dependency: Please install Git (git-core) >= 1.6.5

Prerequisite check failed. Use FORCE=1 to override.
make[2]: *** [/home/linker/devel/turris/omnia-os/include/toplevel.mk:142: staging_dir/host/.prereq-build] Error 1
make[1]: *** [/home/linker/devel/turris/omnia-os/include/toplevel.mk:69: prepare-tmpinfo] Error 2
make: *** [/home/linker/devel/turris/omnia-os/include/toplevel.mk:181: world] Error 2